Butter stick



FIG. 1 is a top, front, left side perspective view of a butter stick;

FIG. 2 is a top plan view thereof, the bottom plan view being a mirror image thereof;

FIG. 3 is a front elevation view thereof, the back elevation view being a mirror image thereof; and,

FIG. 4 is a left side elevation view thereof, the right side elevation view being a mirror image thereof.

The unshaded areas shown in evenly-dashed broken lines in the drawings illustrate the portions of the butter stick that form no part of the claim. Any portion of the article between those breaks forms no part of the claimed design. 

CLAIM The ornamental design for a butter stick, as shown and described. 